For a Wheatstone bridge with R1 = 3000 ohms, R2 = 8000 ohms, and R4 = 15 ohms, what value of R3 would balance the bridge?

To find the value of R3 that will balance the Wheatstone bridge, you can use the formula that defines the balance condition of the bridge:

R1/R2 = R3/R4.

Plugging in the known values, we have:

3000 ohms / 8000 ohms = R3 / 15 ohms.

Now, simplify the left side:

3000 / 8000 = 0.375.

This gives the equation:

0.375 = R3 / 15.

To find R3, multiply both sides by 15:

R3 = 0.375 * 15.

Calculating that gives:

R3 = 5.625 ohms.

This shows that the resistance value of 5.625 ohms is the one required to balance the Wheatstone bridge correctly, verifying that the answer you provided is indeed accurate.